This section provides background information related to the present disclosure which is not necessarily prior art.
Battery cells have plates surrounded by an electrolyte. When the level of electrolyte in the battery cell drops sufficiently, known as dry out, failure of the battery cell can occur. In battery cells allowing for electrolyte to be added, the battery cells are typically checked periodically and electrolyte added to replace any lost electrolyte. One such type of battery is the lead-acid battery and water is added as needed to keep the electrolyte level at a full level.
Sealed batteries, as the name implies, are sealed and do not allow electrolyte to be added to make up for lost electrolyte. A common type of sealed battery is the valve-regulated lead-acid (VRLA) battery.
It is desirable to monitor the electrolyte level of a battery as a low electrolyte level is an indicator of early dry out of the battery making it more likely that the battery will fail. Also, in batteries where electrolyte can be added, monitoring the electrolyte level allows a user to be alerted when electrolyte needs to be added.
Typical approaches for monitoring electrolyte levels in battery cells are intrusive as they are installed within the cells of the batteries. The inside of a battery cell is a highlight corrosive environment, requiring that the components of the monitoring device installed within the cells be made of material that can withstand this environment. Also, the mechanical design of that part of the monitoring device that is installed within a battery cell is specific to the configuration of the battery cell thus requiring differing mechanical designs for battery cells with different configurations.
Ohmic measurements and capacity testing are other technologies that are used to determine dry out of battery cells. Ohmic measurements often cannot identify that dry out is occurring until it has become severe. Capacity testing is often considered the best method of determining dry out, but the equipment tends to be expensive and the process time consuming.